The overall objective of this project is to provide mechanistic insight into the action of a gene gun delivered DNA vaccine against SIV. This SIV/rhesus macaque model system for a therapeutic vaccine will provide important, relevant preclinical animal data prior to the testing of an HIV- 1 DNA vaccine in HIV-1-infected individuals. Critical aspects of any vaccination process include the movement of antigen presenting cells such as dendritic cells (DC) and Langerhan's cells (LC) from antigen delivery sites to immune inductive sites, as well as movement of effector T cells from inductive to effector sites. We propose here to determine the chemokine and chemokine receptor expression patterns at the sites of an adjuvanted DNA vaccination (skin and rectal mucosal). Our hypothesis is that the chemotactic environment is a critical determinant of the success of an SIV or HIV targeted DNA vaccine delivered to either skin or rectal mucosal surfaces. We will investigate the roles played by chemokines and chemokine receptors in the efficacy of a enterotoxin (LT), based on preliminary studies of Deb Fuller (Project 1) and Joel Haynes (PI, Overall Program). Our experience with in situ hybridization (ISH) approaches will be applied to these issues and will provide mechanistic insight into how CT or LT adjuvanted DNA vaccines against SIV elicit potent anti- SIV immune responses. The SPECIFIC AIMS of this Project are to: (1) define the chemotactic signaling and response elements in the DNA vaccine delivery sites (skin or rectal mucosal) and draining lynmph nodes; (2) determine the ability of transgenes encoding rhesus macaques chemokines or chemokine receptor genes to serve as adjuvants and augment the induction of effective SIV-specific immune responses; and (3) determine the timing, location, and target cells for expression of gene gun delivered transgenes. For all 3 of these SPECIFIC AIMS, will be working with Projects 1, 2, and 4, co-coordinating the in vivo studies, tissue acquisition, and analyses. By providing information on the expression of chemokine and chemokine receptor genes during adjuvanted DNA vaccination, we will identify chemotactic signals that are involved in establishing potent and appropriate immune responses during therapeutic vaccination. This will assist in understanding how the gene gun delivered DNA vaccine works, and provide insight into potential ways to improve such strategies. This will assist in understanding how the gene gun delivered DNA vaccine works, and provide insight into potential ways to improve such strategies. This proposal, therefore, will provide mechanistic insight into the role played by chemokine/receptors in immune induction, through a highly interactive and collaborative study with other Projects in this Overall Program.